1. Technical Background
The present invention relates generally to medical devices, and more particularly to applying coatings to catheter shafts.
2. Discussion
Catheters are used in a variety of therapeutic applications, and are available in a variety of types including diagnostic catheters, guiding catheters, balloon catheters, catheter sheath introducers, etc. The present invention relates to systems and methods for applying a coating to one or more catheter shaft components.
By way of example, the present invention will be described in relation to balloon catheters, diagnostic catheters, and guiding catheters. However, it should be understood that the present invention relates to any system or method of coating all or part of one or more medical catheter components, according to the present invention as recited in the following claims, and it is not otherwise limited to angioplasty, or balloon catheters, or any other feature that may be described in this description.
Structurally, many balloon catheters have a relatively long and flexible tubular shaft defining one or more passages or lumens, and an inflatable balloon attached near one end of the shaft.
The end of the catheter where the balloon is located is customarily referred to as the “distal” end, while the other end is called the “proximal” end. The proximal end of the shaft is generally coupled to a proximal hub.
In greater detail, the hub defines a proximal inflation port, and may define a proximal guidewire port. The proximal inflation port communicates with an inflation lumen defined by the shaft, which extends and is connected to the interior of the balloon, for selectively inflating and deflating the balloon.
If the balloon catheter has a guidewire lumen for slidingly receiving a guidewire, the guidewire lumen will extend between a proximal guidewire port, and a distal guidewire port located at the distal end of the catheter. If the proximal guidewire port is defined at the hub, the resulting arrangement is referred to as “over-the-wire.” And if the proximal guidewire port is located at some intermediate point along the shaft, the resulting configuration is called “rapid-exchange.”
Examples of balloon catheters are shown in the following United States patents, all of which are commonly owned with the present invention: (i) U.S. Pat. No. 6,663,648, entitled “Balloon catheter with floating stiffener, and procedure,” issued to Trotta on Dec. 16, 2003; (ii) U.S. Pat. No. 6,364,894, entitled “Method Of Making An Angioplasty Balloon Catheter,” issued to Healy et al. on Apr. 2, 2002; (iii) U.S. Pat. No. 5,820,594, entitled “Balloon Catheter,” issued to Fontirroche et al. on Oct. 13, 1998; and (iv) U.S. Pat. No. 5,370,615, entitled “Balloon Catheter For Angioplasty,” issued to Johnson on Dec. 6, 1994.
Structurally, diagnostic catheters also have a proximal hub affixed to a tubular flexible catheter shaft. Some reinforcement, such as metal wire braid, may be provided in the sidewall of the tubular shaft. In general, diagnostic catheters do not have a balloon.
Similarly, guiding catheters also have a proximal hub affixed to a tubular flexible catheter shaft, which is larger in diameter or lumen size than comparable balloon or diagnostic catheters. Guiding catheters in particular may have a distal tip of a radiopaque material which is visible on an x-ray fluoroscope.
It may be desirable to apply a coating to a portion or all of the shaft component(s) of a catheter. For example, a lubricious coating can reduce friction along portions of the catheter shaft. One particular type of lubricious coating is hydrophilic coatings, which become slippery on contact with water or other liquids.
However, a characteristic of lubricious coatings is of course that they are slippery, and it may be desirable to specifically avoid coating some portions of the catheter. For example, it may be preferred that the catheter shaft proximal end have no coating, so the proximal hub can be securely affixed to the shaft. Another example is that it may be preferred not to apply the coating to a distal end of the catheter shaft. For example, if a balloon will be affixed to the catheter shaft distal end, or if other medical devices such as a stent will be provided, then that portion of the shaft should not have a lubricious coating.
Different types of coating may be applied using the systems and methods of the present invention, including for example anticoagulant coatings or therapeutic coatings such as drug-eluting coatings.
It may be desirable to apply a coating only to a portion of a catheter shaft component, or perhaps only an intermediate portion between that component's proximal and distal ends. In addition, it may be desirable to apply such a partial coating without using a mask or similar techniques and methods.
Likewise, it may also be desirable to provide for an efficient, repeatable and scaleable coating process, as well as a coating process that provides even coating density. Another possibly desirable feature is to provide for evenly drying or curing the coating, without allowing the initial fluid coating to run down and gather at one portion of the shaft component. For example, it is desirable to avoid any droplets of coating materials, or other coating inconsistencies.
It may also be desirable to coat only an intermediate portion of a catheter shaft component, without coating the proximal and distal ends or portions of the catheter shaft component, and also with the even coating aspects mentioned above.
Also, it may be desirable in the case of tubular catheter components defining at least one lumen, to avoid allowing any coating materials to enter inside a lumen.
In addition, it may be desirable to provide coating systems and methods to improve product yield rates during manufacturing.
These and various other objects, advantages and features of the invention will become apparent from the following description and claims, when considered in conjunction with the appended drawings. The invention will be explained in greater detail below with reference to the attached drawings of a number of examples of embodiments of the present invention.